Malignant mesothelioma is a rare cancer of the lining of the lung (pleural mesothelioma) or the lining of the abdomen (peritoneal mesothelioma). The only known cause of mesothelioma in North America is exposure to asbestos.

Like the other asbestos-related diseases, mesothelioma has a long latency period (period of time between first exposure to asbestos and the diagnosis of the disease.). In rare cases the latency period has been as short as 10 to 15 years after the first exposure to asbestos. Typically, however, mesothelioma occurs 20, 30, 40 or more years after the first exposure.

Even low exposures to asbestos can lead to the development of malignant mesothelioma. It is not uncommon for someone to develop this cancer after only a few weeks of exposure at a summer job decades earlier or from washing clothes worn by a worker exposed to asbestos on the job. There are even cases reported in medical literature of mesothelioma developing in people who simply live near a site where asbestos products were used or manufactured.

Malignant mesothelioma is almost always fatal. Survival is usually limited to 12 to 18 months from the diagnosis, sometimes substantially less. There are some people, however, usually relatively young and in good health before being stricken with this disease, who have achieved longer term survival.